Fungicidal insecticidal and acaricidal tin salts of heterocyclic hydroxamic acids

ABSTRACT

Compounds of the formula ##STR1## wherein Het is a 5- or 6-membered aromatic heterocyclic ring containing 1 to 2 ring nitrogen atoms and the remaining ring atoms carbon atoms optionally substituted with 1 to 2 substituents independently selected from halo, nitro, trihalomethyl, lower alkyl of 1 to 3 carbon atoms, or lower alkoxy of 1 to 3 carbon atoms; R is alkyl of 1 to 7 carbon atoms; R 1  is aryl of 6 to 10 carbon atoms, lower alkyl of 1 to 6 carbon atoms, cycloalkyl of 3 to 8 carbon atoms, all optionally substituted with 1 to 3 halogen atoms; and a is 0 or 1 are fungicidal and insecticidal, with the proviso that a ring nitrogen is not bonded to the hydroxamic acid ##STR2## moiety.

BACKGROUND OF THE INVENTION

The present invention relates to tin salts of heterocyclic hydroxamic acids which are active as fungicides.

Various organo-tin compounds have been disclosed as having biocidal activities. See, e.g., U.S. Pat. Nos. 3,657,451; 3,906,103; 3,987,191; and 4,224,338.

U.S. Pat. No. 3,533,993 discloses organo-tin derivatives of 2-mercaptopyridine-1-oxide of the formula: ##STR3## wherein R, R', and R" are independently selected alkyl and preferably lower alkyl, i.e., alkyl having 1-4 carbon atoms; and aryl having 6-10 carbon atoms, preferably phenyl; n and m independently are 0-1 and r is 1-2, with the proviso that n plus m plus r is three, which are useful as heat stabilizers for vinyl chloride resins.

U.S. Pat. No. 4,327,089 discloses certain O-(N-alkoxy-pyridyl) phosphorus esters and thio esters as being insecticidal and acaricidal.

SUMMARY OF THE INVENTION

The present invention relates to novel tin salts of heterocyclic hydroxamic acids of the formula ##STR4## wherein Het is a 5- or 6-membered aromatic heterocyclic ring containing 1 to 2 ring nitrogen atoms and the remaining ring atoms carbon atoms optionally substituted with 1 to 2 substituents independently selected from halo, nitro, trihalomethyl, lower alkyl of 1 to 3 carbon atoms, or lower alkoxy of 1 to 3 carbon atoms; R is alkyl of 1 to 7 carbon atoms; R¹ is aryl of 6 to 10 carbon atoms, lower alkyl of 1 to 6 carbon atoms, cycloalkyl of 3 to 8 carbon atoms, all optionally substituted with 1 to 3 halogen atoms; and a is 0 or 1, with the proviso that a ring nitrogen of Het is not bonded to the hydroxamic acid ##STR5##

Among other factors, the present invention is based on my finding that these compounds are surprisingly active as fungicides. In particular, they may be useful in controlling certain plant fungal infections.

Preferred heterocyclic rings, Het, include pyridyl, pyrazinyl, pyrimidyl, and pyridazinyl.

Preferred substituents on Het include chloro, bromo, nitro, trifluoromethyl, methoxy, or ethoxy.

Preferred R groups include methyl, ethyl, and propyl.

Preferred R¹ groups include n-butyl, cyclohexyl, and phenyl.

Particularly preferred R groups include methyl and ethyl.

Particularly preferred R¹ groups include n-butyl, cyclohexyl, and phenyl.

Preferred are compounds where a is 0.

Preferred trihalomethyl groups include trifluoromethyl.

Representative compounds of this invention are found in Table I.

Definitions

As used herein, the following terms have the following meanings unless expressly stated to the contrary.

The term "alkyl" refers to both straight- and branched-chain alkyl groups. The term "lower alkyl" refers to both straight- and branched-chain alkyl groups having a total of from 1 to 6 carbon atoms and includes primary, secondary and tertiary alkyl groups. Typical lower alkyls include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, and the like.

The term "cycloalkyl" refers to cyclic alkyl groups. The term "lower cycloalkyl" refers to groups having from 3 to 6 carbon atoms in the ring, and includes cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

The term "alkylene" refers to the group --(CH₂)_(m) wherein m is an integer greater than zero. Typical alkylene groups include, methylene, ethylene, propylene and the like.

The term "alkylthio" refers to the group R'S-- wherein R' is alkyl. The term "lower alkylthio" refers to alkylthio groups having 1 to 6 carbon atoms; examples include methylthio, ethylthio, n-hexylthio, and the like.

The term "alkylthioalkylene" refers to an alkyl group substituted with an alkylthio group. The term "lower alkylthioalkylene" refers to groups having up to a total of 8 carbon atoms and includes, for example, ethylthiomethylene, methylthiomethylene, 2-methylthiopropylene, and the like.

The term "alkoxy" refers to the group --OR' wherein R' is an alkyl group. The term "lower alkoxy" refers to alkoxy groups having from 1 to 6 carbon atoms; examples include methoxy, ethoxy, n-hexoxy, n-propoxy, isopropoxy, isobutoxy, and the like.

The term "alkoxyalkylene" refers to an alkyl group substituted with an alkoxy group. The term "lower alkoxyalkylene" refers to groups having up to a total of 8 carbon atoms and includes, for example, ethoxymethylene, methoxymethylene, 2-methoxypropylene, and the like.

The term "alkenyl" refers to unsaturated alkyl groups having a double bond [e.g., CH₃ CH═CH(CH₂)] and includes both straight- and branched-chain alkenyl groups. "Lower alkenyl" refers to groups having a total of from 3 to 6 carbon atoms. Typical lower alkenyl groups include, for example, propenyl, but-3-enyl, hex-4-enyl, 2-methylpent-4-enyl, and the like.

The term "halo" or "halogen" refers to the groups fluoro, chloro, bromo and iodo.

The term "haloalkenyl" refers to alkenyl groups substituted with from 1 to 2 halogen atoms. "Lower haloalkenyl" refers to groups having a total of from 3 to 5 carbon atoms, and includes, for example, 1-chloropropenyl, 2,3-dibromo-but-3-enyl, and the like.

The term "alkynyl" refers to unsaturated alkyl groups having a triple bond (e.g., CH₃ C.tbd.CCH₂ CH₂₋₋) and includes both straight- and branched-chain alkynyl groups. "Lower alkynyl" refers to groups having a total of from 3 to 5 carbon atoms. Typical lower alkynyl groups include propynyl, butynyl, and the like.

The term "hydroxy alkyl" refers to the group --R"OH wherein R" is branched or unbranched alkylene and the hydroxy can be on a primary, secondary or a tertiary carbon. Examples include hydroxy ethyl and 2-hydroxypropyl and 2-hydroxy-2-methyl butyl.

The term "aryl" refers to aryl groups having from 6 to 10 carbon atoms and includes, for example, phenyl, p-chlorophenyl, m-methylphenyl, p-butylphenyl, m-trifluoromethylphenyl, naphthyl, and the like.

The term "aralkyl" refers to an alkyl group of 1 to 4 carbons substituted with an aryl group of from 6 to 10 carbons and includes, for example, benzyl, p-chlorobenzyl, p-methylbenzyl and 2-phenylethyl.

The term "arylthio" refers to the group R'" S-- wherein R'" is an aryl group; examples include phenylthio, naphthylthio, and the like.

The term "arylthioalkyl" refers to an alkyl group of 1 to 4 carbon atoms substituted with an arylthio group and includes, for example, phenylthiomethylene, naphthylthiomethylene, phenylthioethylene, and the like.

The term "alkylamino" refers to the group R' R"N-- wherein R' is alkyl and R" is hydrogen or alkyl. The term "lower alkylamino" refers to alkylamino groups having 1 to 6 carbon atoms. Typical alkylamino groups include methylamino, ethylamino, diethylamino, dimethylamino, and the like.

Pests are any insect, rodent, nematode, fungus, weed, or any form of terrestrial or aquatic plant or animal life or virus, bacterial organism or other microorganism (except those viruses, bacteria or other microorganisms existing in living humans or other living animals) considered injurious to health, the environment or man's economic well-being.

Pesticides are chemical entities or mixtures thereof intended for preventing, destroying, repelling or mitigating any pest.

The term, "pesticide", when not specifically modified or delimited by other words, sometimes includes any one or a combination of the following: the active ingredient, the pesticide formulation or the pesticide product. It may also include baits for attracting and ultimately killing amphibian and reptile pests.

The terms "insecticide" and "insect" as used herein refer to their broad and commonly understood usages rather than to those creatures which, in the strict biological sense, are classified as insects. Thus, the term "insect" is used not only to include small invertebrate animals belonging to the class "Insecta", but also to other related classes of arthropods, whose members are segmented invertebrates having more or fewer than six legs such as spiders, mites, ticks, centipedes, worms, and the like.

Miticides prevent, inhibit or destroy any of the acarine arachnid arthropods (except ticks) which are common pests to cotton, pecans, mushrooms, avocados, wheat, apples, chickens and other life forms.

Nematocides prevent, repel, inhibit or destroy any members of the class Nematoda. These animals, often called threadworms, roundworms and eelworms, are injurious to plants. They feed on roots, stems, leaves or flowers.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the present invention may be conveniently prepared according to the following reaction scheme: ##STR6## wherein Het, R, R¹ and a are as previously defined in conjunction with formula I, b is a base, M is a basically reacting metal compound which is capable of removing the proton from the hydroxyl group of V, and Y is halogen.

Reaction (1) is conducted by combining II, III, and IV in solvent. It is preferred to add II in solvent to a precooled mixture (to about -5° C. to about 0° C.) of III and IV in water/organic solvent, maintaining the cooling during the addition. Suitable organic solvents include methylene chloride, chloroform, toluene, ether, and the like. Certain acid chlorides, II, are commercially available, others may be conveniently prepared from the corresponding carboxylic acid by conventional procedures. Suitable bases, b, include inorganic bases such as potassium carbonate, sodium carbonate, sodium hydroxide, and the like. It is preferred to add an excess of III and IV relative to II, on the order of about 1.10 to about 1.25 equivalents III per equivalent II and about 1.15 to about 1.3 equivalents IV per equivalent II. The reaction is conducted at a temperature of about -15° C. to about 10° C., preferably from about -5° C. to about 0° C., and is generally complete within about 4 to about 6 hours. The product, V, is isolated by conventional procedures such as extraction, filtration, washing, stripping, and the like.

Where Het is a heterocycle having a secondary amine, such as imidazolyl or pyrrolyl, it may be desirable to protect such a nitrogen prior to preparation of the acid chloride, II, in order to minimize side reactions. Methods of adding and removing such protecting groups are conventional techniques well-known to those skilled in the art.

Reaction (2) is conducted by combining approximately equimolar amounts of V and VI in solvent. It may be preferred to add a slight excess of VI relative to V, on the order of about 1.02 to about 1.05 equivalents VI per equivalent V. It is preferred to add VI to V in solvent. Suitable basically reacting metal compounds, M, include alkali (Group IA) metals such as sodium and potassium, also sodium hydride, butyllithium, and the like. Suitable solvents include low molecular weight alcohols such as methanol and ethanol, dimethoxy ethane, tetrahydrofuran, ether, and the like. The reaction is conducted at a temperature of from about 0° C. to about reflux, preferably from about 0° C. to about 20° C., or, for convenience, at ambient temperature, and is generally complete within about 0.5 to about 1.5 hours. The product, VII, is isolated by conventional procedures such as stripping and the like. Alternatively, after stripping of the solvent, product VII may be used directly in Reaction (3) without further isolation.

Reaction (3) is conducted by combining approximately equimolar amounts of VII and VIII in solvent. It is preferred to add VIII to VII in solvent in order to obtain improved yields. Suitable solvents include organic solvents such as dimethoxyethane, tetrahydrofuran, low molecular weight dialkyl ethers, and the like. The reaction is conducted at a temperature of from about 0° C. to about 35° C., preferably from about 5° C. to about 35° C. or at reflux, and is generally complete within about 6 to about 10 hours. The product, I, is isolated by conventional procedures such as stripping, extraction, washing, filtration, and the like.

Utility

The compounds of the present invention are useful in controlling a wide variety of pests.

These compounds are active as fungicides and are particularly effective in controlling a variety of fungi which are deleterious to plants, including plant fungal infections. These compounds are particularly effective in controlling leaf blights caused by organisms such as Phytophthora infestans and Septoria apii. In addition, some of these compounds are useful in controlling early blights caused by organisms such as Alternaria solani, [downy mildews such as that caused by Plasmopara viticola,]and powdery mildew such as that caused by Erisiphe polygoni. However, some of the compounds of this invention may be more fungicidally active than others against particular fungi.

In addition, some of the compounds of this invention show antibacterial activity and may inhibit bacterial growth.

These compounds are also effective as insecticides and acaracides and may be used in controlling a variety of insect and arthropod pests. In particular, these compounds are especially effective as miticides. However, some of these compounds may be more insecticidally and acaricidally active than others against particular pests.

Like most insecticides, they are not usually applied full strength, but are generally incorporated with conventional biologically inert extenders or carriers normally employed for facilitating dispersion of active ingredients for agricultural chemical application, recognizing the accepted fact that the formulation and mode of application may affect the activity of a material. The toxicants of this invention may be applied as sprays, dusts, or granules to the insects, their environment or hostages susceptible to insect attack. They may be formulated as granules of large particle size, powdery dusts, wettable powders, emulsifiable concentrates, solutions, or as any of several other known types of formulations, depending on the desired mode of application.

Wettable powders are in the form of finely divided particles which disperse readily in water or other dispersants. These compositions normally contain from about 5% to 80% insecticide, and the rest inert material, which includes dispersing agents, emulsifying agents and wetting agents. The powder may be applied to the soil as a dry dust, or preferably as a suspension in water. Typical carriers include fuller's earth, kaolin clays, silicas, and other highly absorbent, readily wettable, inorganic diluents. Typical wetting, dispersing or emulsifying agents include, for example: the aryl and alkylaryl sulfonates and their sodium salts; alkylamide sulfonates, including fatty methyl taurides; alkylaryl polyether alcohols, sulfated higher alcohols and polyvinyl alcohols; polyethylene oxides; sulfonated animal and vegetable oils; sulfonated petroleum oils; fatty acid esters of polyhydric alcohols and the ethylene oxide addition products of such esters; and the addition products of long-chain mercaptans and ethylene oxide. Many other types of useful surface-active agents are available in commerce. The surface-active agent, when used, normally comprises from 1% to 15% by weight of the insecticidal composition.

Dusts are freely flowing admixtures of the active insecticide with finely divided solids such as talc, natural clays, kieselguhr, pyrophyllite, chalk, diatomaceous earths, calcium phosphates, calcium and magnesium carbonates, sulfur, lime, flours, and other organic and inorganic solids which act as dispersants and carriers for the toxicant. These finely divided solids have an average particle size of less than about 50 microns. A typical dust formulation useful herein contains 75% silica and 25% of toxicant.

Useful liquid concentrates include the emulsifiable concentrates, which are homogeneous liquid or paste compositions which are readily dispersed in water or other dispersant, and may consist entirely of the insecticide with a liquid or solid emulsifying agent, or may also contain a liquid carrier such as xylene, heavy aromatic naphthas, isophorone, and other nonvolatile organic solvents. For application, these concentrates are dispersed in water or other liquid carrier, and are normally applied as a spray to the area to be treated.

Other useful formulations for insecticidal applications include simple solutions of the active insecticide in a dispersant in which it is completely soluble at the desired concentration, such as acetone, alkylated naphthalenes, xylene, or other organic solvents. Granular formulations, wherein the insecticide is carried on relatively coarse particles, are of particular utility for aerial distribution or for penetration of cover-crop canopy. Pressurized sprays, typically aerosols wherein the active ingredient is dispersed in finely divided form as a result of vaporization of a low-boiling dispersant solvent carrier, such as the Freons, may also be used. All of those techniques for formulating and applying insecticides are well known in the art.

The percentages by weight of the insecticide may vary according to the manner in which the composition is to be applied and the particular type of formulation, but in general comprise 0.5% to 95% of the toxicant by weight of the insecticidal composition.

The insecticidal compositions may be formulated and applied with other active ingredients, including nematocides, insecticides, fungicides, bactericides, plantgrowth regulators, fertilizers, etc. In applying the chemical, an effective amount and concentration of the toxicant of this invention is, of course, employed

The terms "insecticide" and "insect" as used herein refer to their broad and commonly understood usage rather than to those creatures which, in the strict biological sense, are classified as insects. Thus, the term "insect" is used not only to include small invertebrate animals belonging to the class "Insecta", but also to other related classes of arthropods, whose members are segmented invertebrates having more or fewer than six legs, such as spiders, mites, ticks, centipedes, worms, and the like.

When used as fungicides, the compounds of the invention are applied in fungicidally effective amounts to fungi and/or their habitats, such as vegetative hosts and non-vegetative hosts, e.g., animal products. The amount used will, of course, depend on several factors such as the host, the type of fungus, and the particular compound of the invention. As with most pesticidal compounds, the fungicides of the invention are not usually applied full strength, but are generally incorporated with conventional, biologically inert extenders or carriers normally employed for facilitating dispersion of active fungicidal compounds, recognizing that the formulation and mode of application may affect the activity of the fungicide. Thus, the fungicides of the invention may be formulated and applied as granules, as powdery dusts, as wettable powders, as emulsifiable concentrates, as solutions, or as any of several other known types of formulations, depending on the desired mode of application.

Wettable powders are in the form of finely divided particles which disperse readily in water or other dispersants. These compositions normally contain from about 5% to 80% fungicide, and the rest inert material, which includes dispersing agents, emulsifying agents and wetting agents. The powder may be applied to the soil as a dry dust, or preferably as a suspension in water. Typical carriers include fuller's earth, kaolin clays, silicas, and other highly absorbent, readily wettable, inorganic diluents. Typical wetting, dispersing or emulsifying agents include, for example: the aryl and alkylaryl sulfonates and their sodium salts; alkylamide sulfonates, including fatty methyl taurides; alkylaryl polyether alcohols, sulfated higher alcohols and polyvinyl alcohols; polyethylene oxides; sulfonated animal and vegetable oils; sulfonated petroleum oils; fatty acid esters of polyhydric alcohols and the ethylene oxide addition products of such esters; and the addition products of long-chain mercaptans and ethylene oxide. Many other types of useful surface-active agents are available in commerce. The surface-active agent, when used, normally comprises from 1% to 15% by weight of the fungicidal composition.

Dusts are freely flowing admixtures of the active fungicide with finely divided solids such as talc, natural clays, kieselguhr, pyrophyllite, chalk, diatomaceous earths, calcium phosphates, calcium and magnesium carbonates, sulfur, lime, flours, and other organic and inorganic solids which act as dispersants and carriers for the toxicant. These finely divided solids have an average particle size of less than about 50 microns. A typical dust formulation useful herein contains 75% silica and 25% of toxicant.

Useful liquid concentrates include the emulsifiable concentrates, which are homogeneous liquid or paste compositions which are readily dispersed in water or other dispersant, and may consist entirely of the fungicide with a liquid or solid emulsifying agent, or may also contain a liquid carrier such as xylene, heavy aromatic naphthas, isophorone, and other nonvolatile organic solvents. For application, these concentrates are dispersed in water or other liquid carrier, and are normally applied as a spray to the area to be treated.

Other useful formulations for fungicidal applications include simple solutions of the active fungicide in a dispersant in which it is completely soluble at the desired concentration, such as acetone, alkylated naphthalenes, xylene, or other organic solvents. Granular formulations, wherein the fungicide is carried on relatively coarse particles, are of particular utility for aerial distribution or for penetration of cover-crop canopy. Pressurized sprays, typically aerosols wherein the active ingredient is dispersed in finely divided form as a result of vaporization of a low-boiling dispersant solvent carrier, such as the Freons, may also be used. All of those techniques for formulating and applying fungicides are well known in the art.

The percentages by weight of the fungicide may vary according to the manner in which the composition is to be applied and the particular type of formulation, but in general comprise 0.5% to 95% of the toxicant by weight of the fungicidal composition.

The fungicidal compositions may be formulated and applied with other active ingredients, including other fungicides, insecticides, nematocides, bactericides, plant-growth regulators, fertilizers, etc.

A further understanding of the invention can be had in the following non-limiting Examples. Wherein, unless expressly stated to the contrary, all temperature ranges refer to the Centigrade system and the term "ambient" or "room temperature" refers to about 20° C. to about 25° C. The term "percent" refers to gram moles. The term "equivaleht" refers to a quantity of reagent equal in moles, to the moles of the preceding or succeeding reagent recited in that example in terms of finite moles or finite weight or volume. Also, unless expressly stated to the contrary, geometric isomer and racemic mixtures are used as starting materials and correspondingly, isomer mixtures are obtained as products.

EXAMPLES Example 1 Preparation of N-Methoxy-2-Picolinyl Hydroxamic Acid ##STR7##

(a) To a stirred mixture of 31.1 g (0.25 moles) in methylene chloride with a catalytic amount of pyridine, 35.7 g (0.3 moles) thionyl chloride in methylene chloride were slowly added dropwise. The reaction mixture [was] slightly warmed (to about 35° C.). The reaction mixture was refluxed for 16 hours, until no further hydrogen chloride evolution was observed. The methylene chloride and excess thionyl chloride were removed by reduced pressure and heat to give the picolinic acid chloride which was used in step (b) without further purification.

(b) Methylene chloride (about 200 ml) was added to the picolinic acid chloride from step (a); the resulting mixture was stirred to produce a slurry.

A mixture of 25 g (0.3 moles) methoxyamine hydrochloride and 42 g (0.3 moles) potassium carbonate in about 300 ml water at about 0° C. was prepared. To that aqueous mixture, the acid chloride/methylene chloride slurry was added, maintaining the temperature of the mixture at about 0° C. The reaction mixture was stirred for 4 hours. The phases were separated. The methylene chloride layer was dried over magnesium sulfate, filtered, and stripped to give about 15.1 g of the above-identified product, as an amber liquid.

Elemental analysis for C₇ H₈ N₂ O₂ showed: calculated % C 55.3, % H 5.3, and % N 18.4; found % C 52.0, % H 5.14, and % N 18.76.

Example 2 Preparation of Triphenylstannyl O-(N-Methoxy-2-Pyridyl Carboximidoate) ##STR8##

(a) To a stirred solution of 2.3 g (0.015 mole) N-methoxy-2-picolinyl hydroxamic acid (the product of Example 1) in about 100 ml methanol, 0.4 g (0.017 mole) sodium metal were added slowly, stirring until the sodium metal had dissolved. The methanol was then removed under reduced pressure and heat to give the sodium salt of the hydroxamic acid which was used in step (b) without further purification.

(b) Dimethoxy ethane (about 100 ml) was added to the sodium salt from step (a). To that stirred mixture, 5.5 g (0.0145 moles) triphenyl tin chloride was added in one portion. The reaction mixture was refluxed 4 hours. The reaction mixture was stirred at ambient temperature over the weekend. The reaction mixture was then refluxed for an additional 4 hours. Dimethoxy ethane was removed under reduced pressure and heat. Water (about 25 ml) and methylene chloride (about 150 ml) were added to the residue and the resulting mixture was stirred. The layers were phase separated. The methylene chloride layer was dried over magnesium sulfate, filtered, and stripped to give the crude product, which was treated with charcoal, celite, and methylene chloride, filtered and stripped to give the above-identified product.

Elemental analysis for C₂₅ H₂₂ N₂ O₂ Sn showed: calculated % C 59.9, % H 4.43, and % N 5.59; found % C 58.5, % H 4.65, and % N 3.45.

Example 3 Preparation of N-Methoxy-2-Pyrazinyl Hydroxamic Acid ##STR9##

(a) A mixture of 68.2 g (0.55 moles) 2-pyrazine carboxylic acid and methylene chloride (about 200 ml) containing a catalytic amount of pyridine was warmed (to about 30° C.). To that mixture, 78.5 g (0.66 mole) thionyl chloride was added dropwise. The reaction mixture was refluxed for 24 hours. The methylene chloride was removed under reduced pressure and heat to give the 2-pyrazine carboxylic acid chloride which was used in step (b) without further isolation.

(b) Methylene chloride (about 150 ml) was added to the acid chloride from step (a).

A mixture of 30 g (0.637 moles) methyoxyamine hydrochloride and 88 g (0.637 moles) potassium carbonate in about 50 ml water was cooled to about -5° C. That mixture and the acid chloride mixture were combined maintaining the temperature of about 0°-5° C. during the addition. The reaction mixture was stirred at ambient temperature for 5 hours. The phases were separated. The organic phase was dried over magnesium sulfate, filtered, and stripped to give about 17 g of the above-identified product as a yellow solid, melting point 104°-112° C.

Elemental analysis for C₆ H₇ N₃ O₂ showed: calculated % C 47.1, % H 3.95, and % N 27.4; found % C 46.4, % H 4.27, and % N 28.0.

Example 4 Preparation of Tricyclohexylstannyl O-(N-Methoxy-2-Pyrazinyl Carboximidoate) ##STR10##

(a) To a stirred mixture of 3.3 g (0.0215 moles) N-methoxy-2-pyrazinyl hydroxamic acid (the product of Example 3) in about 100 ml methanol, 0.5 g (0.022 moles) sodium metal were added slowly. After the sodium metal had dissolved, 6.7 g (0.015 moles) tricyclohexyl tin chloride was added. The reaction mixture was refluxed for 8 hours. Methanol was removed under reduced pressure and heat. Water (about 25 ml) and methylene chloride (about 150 ml) were added to the residue and the resulting mixture was stirred. The layers were phase separated. The methylene chloride layer was dried with magnesium sulfate, filtered, and stripped to give 6 g of the above-identified product, as a yellow solid.

Elemental analysis for C₂₄ H₄₀ N₃ O₂ Sn showed: calculated % C 55.3, % H 7.73, and % N 8.06; found % C 56.94, % H 8.6, and % N 1.11.

Compounds made in accordance with the methods described in the Detailed Description of the Invention and in Examples 1 to 4 and using the appropriate starting materials are found in Table I.

In addition, by following the procedures disclosed in the Detailed Description of the Invention and

in Examples 1 to 4 and using the appropriate starting materials and reagents, the following compounds are made:

Tri-n-butylstannyl O-(N-methoxy-2-pyridyl carboximi- doate);

Tri-n-butylstannyl O-(N-methoxy-3-pyridyl carboximi doate);

Tricyclohexylstannyl O-(N-methyoxy-3-pyridyl carboxi- midoate);

Triphenylstannyl O-(N-methoxy-3-pyridyl carboximidoate);

Tri-n-butylstannyl O-(N-methoxy-4-pyridyl carboximidoate);

Tricyclohexylstannyl O-(N-methoxy-4-pyridyl carboximidoate);

Triphenylstannyl O-(N-methoxy-4-pyridyl carboximidoate;

Tri-n-butylstannyl O-(N-ethoxy-2-pyridyl carboximidoate;

Tricyclohexy O-(N-ethoxy-2-pyridyl carboximidoate);

Triphenylstannyl O-(N-methoxy-2-pyridyl carboximidoate;

Triphenylstannyl O-(N-ethoxy-3-pyridyl carboximidoate;

Tricyclohexylstannyl O-(N-ethoxy-4-pyridyl carboximidoate);

Tri-n-butylstannyl O-[N-methoxy-2-(5-trifluoromethylpyridyl) carboximidoate];

Tricyclohexylstannyl O-[N-methoxy-2-(5-trifluoromethylpyridyl) carboximidoate];

Triphenylstannyl O-[N-methoxy-2-(5-trifluoromethylpyridyl) carboximidoate];

Triphenylstannyl O-[N-ethoxy-2-(5-trifluoromethylpyridyl) carboximidoate];

Tri-n-butylstannyl O-(N-methoxy-2-pyrazinyl carboximidoate);

Triphenylstannyl O-(N-methoxy-2-pyrazinyl carboximidoate);

Tri-n-butylstannyl O-(N-ethoxy-2-pyrazinyl carboximidoate);

Tricyclohexylstannyl O-(N-ethoxy-2-pyridyl carboximidoate);

Triphenylstannyl O-(N-ethoxy-2-pyrazinyl carboximidoate);

Tri-n-butylstannyl O-(N-methoxy-2-pyrimidyl carboximidoate);

Tricyclohexylstannyl O-(N-methoxy-2-pyrimidyl carboximidoate);

Triphenylstannyl O-(N-methoxy-2-pyrimidyl carboximidoate);

Tri-n-butylstannyl O-(N-ethoxy-2-pyrimidyl carboximidoate);

Tricyclohexylstannyl O-(N-ethoxy-2-pyrimidyl carboximidoate);

Triphenylstannyl O-(N-ethoxy-2-pyrimidyl carboximidoate);

Tri-n-butylstannyl O-(N-methoxy-4-pyridazinyl carboximidoate);

Tricyclohexylstannyl O-(N-methoxy-4-pyridazinyl carboximidoate);

Triphenylstannyl O-(N-methoxy-4-pyridazinyl carboximidoate);

Tri-n-butylstannyl O-(N-methoxy-5-pyrimidyl carboximidoate);

Tricyclohexylstannyl O-(N-ethoxy-5-pyrimidyl carboximidoate);

Triphenylstannyl O-(N-methoxy-5-pyrimidyl carboximidoate);

Triphenylstannyl O-(N-ethoxy-5-pyrimidyl carboximidoate);

Tri-n-butylstannyl O-(N-methoxy-2-pyrrolyl carboximidoate);

Tricyclohexylstannyl O-(N-methoxy-2-pyrrolyl carboximidoate);

Triphenylstannyl O-(N-methoxy-2-pyrrolyl carboximidoate);

Tri-n-butylstannyl O-(N-methoxy-3-pyrazolyl carboximidoate);

Tricyclohexylstannyl O-(N-methoxy-3-pyrazolyl carboximidoate);

Triphenylstannyl O-(N-methoxy-3-pyrazolyl carboximidoate);

Tri-n-butylstannyl O-[N-methoxy-5-(1-methylimidazolyl) carboximidoate];

Tricyclohexylstannyl O-[N-methoxy-5-(1-methylimidazolyl) carboximidoate]; and

Triphenylstannyl O-[N-methoxy-5-(1-methylimidazolyl) carboximidoate].

Example A Bacterial Inhibition

Compounds of this invention were evaluated for in vitro bactericidal effectiveness by means of a bacterial inhibition test. This test is designed to measure the antibacterial activity of compounds in terms of degree of inhibition bacterial multiplication. The representative bacteria used were Erwinia amylovora, Pseudomonas syringae and Xanthomonas vesicatoria. Each compound to be tested was dissolved in acetone to give a 500 ppm concentration. Agar plates were inoculated using a micro sprayer with an suspension of the particular bacteria shortly (3 to 5 seconds) before treatment. The inoculated agar plates were then treated with the compound to be tested by spraying with a micro sprayer. The treated plates were incubated at 23.5° C. and the data was taken 24 hours after treatment. Antibacterial activities are measured by a zone of inhibited bacterial growth from the center of the agar plate and the deposit concentration in mg/cm² at the edge of the zone of inhibition (ED₉₉). The effectiveness of the compounds for antibacterial activity are reported in Table II in terms of the percent of the ED₉₉ of each compound of the ED₉₉ of the standard PMA (phenyl mercuric acetate).

Example B Mycelial Inhibition

Compounds were evaluated for in vitro fungicidal effectiveness by means of a mycelial inhibition test. This test is designed to measure the fungitoxic activity of fungicidal chemicals in terms of their degree of inhibition of mycelium growth. Fungi used were Pythium ultimum, Rhizoctonia solani, Fusarium moniloforme, Botrytis cinerea, Aspergillus niger and Ustilago hordeii. Each compound to be tested was dissolved in acetone to 500-ppm concentration. Paper strips were infused with the particular mycelium growth by covering the paper with a potato dextrose broth culture of mycelial suspension. The papers were then placed on potato dextrose agar plates and sprayed by means of a micro sprayer with the fungicidal solution. The treated paper strips were incubated at 25° C. and the data is taken after 24 hours. Fungicidal activities are measured by a zone of inhibited mycelial growth from the center of the paper strip in terms of mg/cm² needed for 991/2 control of the fungus (ED₉₉). The effectiveness of the compounds for fungicidal activity are reported in Table III in terms of the percent of the ED₉₉ of the test compound of the ED₉₉ of the standard Difolatan®.

Example C Grape Downy Mildew

Compounds were tested for the control of the Grape Downy Mildew organism, Plasmopara viticola. Seedlings of Vitis vinifera var. Emperor (7+weeks old) were used as hosts. The plants were sprayed with a 200 ppm solution of the test compound in an acetone and water solution containing a small amount of nonionic emulsifier. The treated plants were inoculated one day later by spraying them with a spore suspension of the organism. The treated plants were then held in a greenhouse at a temperature of about 68° F. to about 72° F. (relative humidify varied between about 30 and about 99%) for 4 days. The plants were then placed in an environmental chamber at 100% relative humidity to induce sporulation. On removal from the chamber and after drying, the plants were evaluated for disease development. The percent disease control provided by a given test compound was based on the percent disease reduction relative to untreated check plants. The results are reported in Table III.

Example D Tomato Late Blight

Compounds were tested for the preventative control of the Tomato Late Blight organism Phytophthora infestans. Five- to six-week-old tomato (cultivar Bonny Best) seedlings were used. The tomato plants were sprayed with a 200-ppm suspension of the test compound in acetone, water and a nonionic emulsifier. The sprayed plants were then inoculated 1 day later with the organism, placed in an environmental chamber and incubated at 66° F. to 68° F. and 100% relative humidity for at least 16 hours. Following the incubation, the plants were maintained in a greenhouse for approximately 7 days. The percent disease control provided by a given test compound was based on the percent disease reduction relative to untreated check plants. The results are tabulated in Table III.

Example E Rice Blast

Compounds of this invention were tested for control of the Rice Blast organism Piricularia oryzae, using 10- to 14-day-old rice plant seedlings (Calrose M-9 variety). Seedling plants were sprayed with a 625-ppm solution of the test compound in acetone, water and a nonionic emulsifier (ORTHO X-77 spreader). The sprayed plants were inoculated 1 day later with the organism in an environmental chamber. After inoculation, the plants were kept in an environmental chamber for about 48 hours under conditions of about 72° F. to 75° F. and about 100% relative humidity. Following the incubation period, the plants were placed in a greenhouse with a temperature of about 72° F. and maintained with bottom watering for about 12 to 16 days. The percent disease control provided by a given test compound is based on a comparison of the percentage disease relative to the percent disease development on the untreated check plants: ##EQU1## The results are tabulated in Table III.

Example F Tomato Early Blight

Compounds were tested for the control of the Tomato Early Blight organism Alternaria solani. Tomato (variety Bonny Best) seedlings of 6- to 7-weeks old were used. The tomato plants were sprayed with a 200-ppm solution of the test compound in an acetone-and-water solution containing a small amount of a nonionic emulsifier. The sprayed plants were inoculated 1 day later with the organism, placed in the environmental chamber and incubated at 66° F. to 68° F. and 100% relative humidity for 24 hours. Following the incubation, the plants were maintained in a greenhouse for about 12 days. Percent disease control was based on the percent disease development on untreated check plants. The results are tabulated in Table III.

Example G Celery Late Blight

The Celery Late Blight tests were conducted using celery (Utah) plants 11 weeks old. The Celery Late Blight organism was Septoria apii. The celery plants were sprayed with 200-ppm solutions of the candidate toxicant mixed with acetone, water and a nonionic emulsifier. The plants were then inoculated with the organism and placed in an environmental chamber and incubated at 66° F. to 68° F. in 100% relative humidity for an extended period of time (approximately 48 hours). Following the incubation, the plants were allowed to dry and then were maintained in a greenhouse for approximately 14 days. The percent disease control provided by a given test compound is based on the percent disease reduction relative to untreated check plants. The results are reported in Table III.

Example H Bean Powdery Mildew

Compounds were tested for the control of the Bean Powdery Mildew organism Erysiphe polygoni. Seedling bean plants were sprayed with a 250-ppm solution of the test compound in acetone, water and a nonionic emulsifier. The sprayed plants were then inoculated 1 day later with the organism. The plants were maintained for 10 days at temperatures of 68° F. at night with daytime temperatures of 72° F. to 80° F.; relative humidity was maintained at 40% to 60%. The percent disease control provided by a given test compound was based on the percent disease reduction relative to the untreated check plants. The results as percent control are tabulated in Table III.

Example I Bean Rust

Compounds were evaluated for their ability to eradicate Bean Rust caused by Uromyces phaseoli typica on pinto beans.

Pinto bean plants, variety Idaho 1-11, 16 (summer) or 19 (winter) days old were inoculated with a 50-ppm suspension of uredospores in water containing a small amount of nonionic surfactant. The inoculated plants were placed in an environmental chamber immediately after inoculation and incubated 20 hours. Following the incubation period, the plants were removed from the chamber and placed in a greenhouse maintained at 66-68° F. and 60-80% relative humidity. Two days after inoculation, the plants were treated by spraying with a 200-ppm solution of test compound in an acetone and water carrier formulation containing a small amount of nonionic surfactant. One or two replicate pots (each containing two plants) were used for each compound. In addition one or two replicate pots were sprayed with the same carrier formulation (without a test compound) as a control (hereinafter "untreated Checks"). The plants were kept in the greenhouse until evaluated. The plants were evaluated for disease control when disease symptoms were well developed on the untreated Checks, normally about 14 days after treatment. The percentage disease control (or eradication) provided by a test compound was based on the percent disease reduction relative to the untreated Checks. The results are reported in Table III.

Example J Aphid Control

The compounds of this invention were tested for their insecticidal activity against cotton aphids (Aphis gossypii Glover). An acetone solution of the test compound containing a small amount of nonionic emulsifier was diluted with water to give a concentration of 40 ppm. Cucumber leaves infested with cotton aphids were dipped in the test compound solution. Mortality readings were taken after 24 hours. The results are tabulated in Table II in terms of percent control.

Example K Aphid Systemic Evaluation

This procedure is used to assess the ability of a candidate insecticide to be absorbed through the plant root system and translocate to the foliage and thus to show insecticidal activity against the cotton aphid (Aphis gossypii Glover).

Two cucumber plants planted in a 4-inch fiber pot with a soil surface area of 80 cm² are used. Forty ml of an 80-ppm solution of the candidate insecticide is poured around the plants in each pot. (This corresponds to 40 gamma/cm² of actual toxicant.) The plants are maintained throughout in a greenhouse at 75°-85° F. Forty-eight hours after the drenching, the treated plants are infested with aphids by placing well-colonized leaves over the treated leaves so as to allow the aphids to migrate easily from the inoculated leaf to the treated leaf. Three days after infestation, mortality readings were taken. The results are tabulated in Table IV in terms of percent control.

Example L Mite Adult

Compounds of this invention were tested for their insecticidal activity against parathion-resistant Two-spotted Spider Mite (Tetranychus urticae Koch). An acetone solution of the candidate toxicant containing a small amount of nonionic emulsifier was diluted with water to 40 ppm. Lima bean leaves which were infested with mites were dipped in the toxicant solution. The results are tabulated in Table IV in terms of percent control.

Example M Mite Egg Control

Compounds of this invention were tested for their ovicidal activity against eggs of the two-spotted spider mite (Tetranychus urticae Koch). An acetone solution of the test toxicant containing a small amount of nonionic emulsifier was diluted with water to give a concentration of 40 ppm. Two days before testing, 2-week old lima bean plants were infested with spider mites. Two days after infestation, leaves from the infested plants are dipped in the toxicant solution, placed in a petridish with filter paper and allowed to dry in the open dish at room temperature. The treated leaves were then held in covered dishes at about 31° C. to 33° C. for seven days. On the eighth day egg mortality readings are taken. The results, expressed as percent control, are tabulated in Table IV.

Example N Housefly

Compounds of this invention were tested for their insecticidal activity against the Housefly (Musca domestica Linnaeus). A 500-ppm acetone solution of the candidate toxicant was placed in a micro sprayer (atomizer). A random mixture of anesthetized male and female flies was placed in a container and 55 mg of the above-described acetone solution was sprayed on them. A lid was placed on the container. A mortality reading was made after 24 hours. The results are tabulated in Table IV in terms of percent control.

Example O American Cockroach

Compounds of this invention were tested for their insecticidal activity against Chlorodane-resistant American Cockroaches (Periplaneta americana Linnaeus). A 500-ppm acetone solution of the candidate toxicant was placed in a micro sprayer (atomizer). A random mixture of anesthetized male and female roaches was placed in a container and 55 mg of the above-described solution was sprayed on them. A lid was placed on the container. A mortality reading was made after 24 hours. The results are tabulated in Table IV in terms of percent control.

Example P Alfalfa Weevil

The compounds of this invention were tested for their insecticidal activity against Alfalfa Weevil (Hypera brunneipennis Boheman). A 500-ppm acetone solution of the candidate toxicant was placed in a micro sprayer (atomizer). A random mixture of male and female weevils was placed in a container and 55 mg of the above-described acetone solution was sprayed on them. A lid was placed on the container. A mortality reading was made after 24 hours. The results are tabulated in Table IV in terms of percent control.

Example Q Cabbage Looper Control

The compounds of this invention were tested for their insecticidal activity against Cabbage Looper (Trichoplusia ni Hubner). An acetone solution of the candidate toxicant containing a small amount of nonionic emulsifier was diluted with water to give a concentration of 500 ppm. Excised cucumber leaves were dipped in the toxicant solution and allowed to dry. The leaves were then infested with Cabbage Looper larvae. Mortality readings were taken after 24 hours. The results are tabulated in Table IV in terms of percent control.

                                      TABLE I                                      __________________________________________________________________________     Compounds of the Formula:                                                       ##STR11##                                                                                                      ELEMENTAL ANALYSIS                                                             % C    % H    % N                             Compound                                                                             Het    R   R.sup.1                                                                               Physical State                                                                          Calc.                                                                             Found                                                                              Calc.                                                                             Found                                                                              Calc.                                                                             Found                        __________________________________________________________________________     1 44020                                                                               ##STR12##                                                                            CH.sub.3                                                                            ##STR13##                                                                            pale yellow solid, m.p. 162-165° C.                                              57.8                                                                              56.3                                                                               7.76                                                                              8.44                                                                               5.39                                                                              2.48                         2 44675                                                                               ##STR14##                                                                            CH.sub.3                                                                            ##STR15##                                                                            viscous opaque liquid                                                                   59.9                                                                              58.5                                                                               4.43                                                                              4.65                                                                               5.59                                                                              3.45                         3 43984                                                                               ##STR16##                                                                            CH.sub.3                                                                            ##STR17##                                                                            yellow solid, m.p. 173-180° C.                                                   55.3                                                                              56.9                                                                               7.73                                                                              8.6 8.06                                                                              1.11                         __________________________________________________________________________

                                      TABLE II                                     __________________________________________________________________________     FUNGICIDAL ACTIVITY                                                            Mycelial Inhibition                                                            Compound                                                                             Pyth.                                                                             Rhiz.                                                                             Fusar.                                                                             Botry.                                                                             Asper.                                                                             Ustil.                                                                             TLB                                                                               RB TEB                                                                               CLB                                                                               BPM                                                                               BR                                  __________________________________________________________________________     1 44020                                                                              0  0  0   0   0   0   91 0  43 96 100                                                                               0                                   2 44675                                                                              23 0  0   14  50  0   95 30 63 100                                                                               100                                                                               0                                   3 43984                                                                              0  0  96  0   0   100 50 0   0 63  97                                                                               0                                   __________________________________________________________________________

                  TABLE III                                                        ______________________________________                                         INSECTICIDAL ACTIVITY                                                          Com-                                                                           pound AR     AW     HF   MA   ME   Aph. AS   CL   5-CL                         ______________________________________                                         1 44020                                                                              0      0      0    0    100  0    0    0    100                          2 44675                                                                              0      --     0    0     0   0    0    0    90                           3 43984                                                                              30     0      80   40   80   0    0    20    0                           ______________________________________                                     

What is claimed is:
 1. A compound of the formula ##STR18## wherein Het is a 6-membered aromatic heterocyclic ring containing 1 ring nitrogen atom and the remaining ring atoms carbon atoms optionally substituted with 1 to 2 substituents independently selected from halo, nitro, trihalomethyl, lower alkyl of 1 to 3 carbon atoms, or lower alkoxy of 1 to 3 carbon atoms; R is alkyl of 1 to 7 carbon atoms; R¹ is aryl of 6 to 10 carbon atoms, lower alkyl of 1 to 6 carbon atoms, cycloalkyl of 3 to 8 carbon atoms, all optionally substituted with 1 to 3 halogen atoms; and a is 0 or 1, with the proviso that a ring nitrogen is not bonded to the hydroxamic acid ##STR19## moiety.
 2. A compound according to claim 1 wherein Het is unsubstituted pyridyl.
 3. A compound according to claim 2 wherein a is
 0. 4. A compound according to claim 3 wherein R¹ is cycloalkyl or aryl.
 5. A compound according to claim 4 wherein Het is 3-pyridyl.
 6. A compound according to claim 5 wherein R¹ is cyclohexyl.
 7. A compound according to claim 5 wherein R¹ is phenyl.
 8. A method of controlling fungi which comprises contacting said fungi or their growth environment with a fungicidally effective amount of a compound of claim
 1. 9. A method of controlling fungi which comprises contacting said fungi or their growth environment with a fungicidally effective amount of a compound of claim
 2. 10. A method of controlling fungi which comprises contacting said fungi or their growth environment with a fungicidally effective amount of a compound of claim
 3. 11. A method of controlling fungi which comprises contacting said fungi or their growth environment with a fungicidally effective amount of a compound of claim
 4. 12. A method of controlling fungi which comprises contacting said fungi or their growth environment with a fungicidally effective amount of a compound of claim
 6. 13. A method of controlling fungi which comprises contacting said fungi or their growth environment with a fungicidally effective amount of a compound of claim
 7. 14. A fungicidal composition which comprises an inert carrier and a fungicidally effective amount of a compound of claim
 1. 15. A fungicidal composition which comprises an inert carrier and a fungicidally effective amount of a compound of claim
 2. 16. A fungicidal composition which comprises an inert carrier and a fungicidally effective amount of a compound of claim
 3. 17. A fungicidal composition which comprises an inert carrier and a fungicidally effective amount of a compound of claim
 4. 18. A fungicidal composition which comprises an inert carrier and a fungicidally effective amount of a compound of claim
 6. 19. A fungicidal composition which comprises an inert carrier and a fungicidally effective amount of a compound of claim
 7. 20. A method of killing insects which comprises contacting said insect or its environment with an insecticidally effective amount of a compound of claim
 1. 21. A method of killing insects which comprises contacting said insect or its environment with an insecticidally effective amount of a compound of claim
 6. 22. An insecticidal composition comprising a biologically inert carrier and an insecticidally effective amount of a compound of claim
 1. 23. An insecticidal composition comprising a biologically inert carrier and an insecticidally effective amount of a compound of claim
 6. 24. A method of killing acarines which comprises contacting said acarine or its environment with an acaricidally effective amount of a compound of claim
 1. 25. A method of killing acarines which comprises contacting said acarine or its environment with an acaricidally effective amount of a compound of claim
 6. 26. An acaricidal composition which comprises a biologically inert carrier and an acaricidally effective amount of a compound of claim
 1. 27. An acaricidal composition which comprises a biologically inert carrier and an acaricidally effective amount of a compound of claim.
 6. 